Seismic surveys are extensively used in the oil and gas industry to understand the subsurface and to provide structural images of the geological formation within the earth using reflected sound waves. The results of the survey are used to identify reservoir size, shape and depth as well as porosity and the existence of fluids. Geophysicists and geologists use this information to pinpoint the most likely locations for successfully drilling for oil and natural gas.
The seismic survey is conducted by placing a large number of geophones in the area of interest. They are set up in lines or in grids. Using shakers or small explosives, the ground is shaken and the geophones acquire the reflected sound data from the different sub-layers in the ground. A huge amount of data is collected in a given seismic survey which can cover 40 sq km and take days to gather.
The amount of data which is retrieved during a seismic survey is quite large. In an exemplary case a geophone measures three axes at a sampling rate of 4 bytes per millisecond (each byte is 8 bits giving a resolution of 24 bits which is the accuracy required by the seismic survey). In this case, the data rate per geophone is:4 bytes/msec×8 bits/byte×3=96 kbps (Kilobits per second)
If the survey is using 1000 geophones, the data rate is then 96 Mbps (Mega bits per second). Because wireless systems have overhead and error correction to operate reliably, even the highest data rate broadband wireless systems can't accommodate this data rate in traditional configurations such as point to multipoint or pure mesh systems.
Several patents are known that use wireless links in a seismic network, including U.S. Pat. Nos. 6,424,931; 6,041,283; 6,219,620; and 7,224,642. However, there is room for improvement in the manner in which data is collected and delivered for processing.